1. Field of the Invention
The present invention relates to a technique for constructing a controller such as a plant of an automobile, and more specifically to a technique for performing gain scheduled control by describing a plant by a linear-parameter variant model and converting the plant into linear matrix inequalities.
2. Description of Background
In conventional prior art methodology, to control a plant in which a constitutive parameter changes during operation, certain methodology is used that introduces variable structure control which performs the controlling function while estimating a state variable by adjusting a gain of an observer by a data map has been employed in many cases.
However, these conventional methods require a lot of efforts especially to incorporate all possibility in a data map. Further, when a map is made experimentally, it is difficult to handle the parameter change of the plant. In view of this, a gain scheduled control, which covers all cases in such a manner that a plant is described by a linear parameter-varying (LPV: Linear Parameter-Varying) model, and a variation range constraint is converted into linear matrix inequalities (LMI: Linear Matrix Inequalities), has been examined as one solution. Nonetheless, in the conventional techniques, the selection of scheduling parameter candidates to obtain sufficient performances was difficult. The selection was human-intensive and required special measures and subjective determination by observing a Bode diagram. This took time and made it difficult to choose the most suitable parameter candidate. The.
Consequently, it is desirable to implement a technique capable of automatically constructing a controller that calculates ν gaps for each candidate of a plant parameter vector. It is desirous that the automatically constructed controller be based on these ν gaps calculated for each candidate of a scheduling parameter vector.